At that time it was in fact two one-act operas but since it's been changed to one name "The Sound of a Voice." I realized it somewhat at the time that this piece is quietly but hugely important in Glass' work. 2003 was the same time as The Hours. It was before Glass' career as a main stream film composer took off (strange to say a composer was discovered by Hollywood when he was 66 years old) and the film offers came rolling in.
The subject matter of these "death plays" right up Glass' alley. Musically, I remember thinking at the time how close to Sprechstimme the vocal writing was, as well as the unorthodox instrumentation which they advertised as "Eastern." Glass stated that he was interested in the challenge of writing for instruments which didn't play chords: flute, cello, pipa, and percussion. Anyway, you could tell that in every way this piece was challenging to compose and the reward came in experiences the opera(s). The work was done a lot when it was new, as it was done in Chicago after Boston and somewhat recently it was done in Pittsburgh. This clip comes from Italy and David Henry Hwang's libretto has been translated into Italian which will make it easier to listen to for some.
The opera has never been released on recording save for a 20 minute suite was which released on "from the Philip Glass Recording Archive, Vol. I: Theater Music" in which the vocal lines are replaced in an arrangement by the composer.